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Friday, May 25, 2012

Astronomy Picture of the Day

Cosmic dust cloudsdim the lightof background stars. But they also
reflect the light of stars nearby.

Since bright stars tend to radiate strongly in the
blue portion of the visible spectrum, and the interstellardust scatters
blue lightmore strongly than
red, the dusty reflection nebulae tend to be blue.

Lovely examples are the wispy blue reflection
nebulae near bright, hot starsPi and Delta Scorpii(upper left and lower right) in thistelescopic skyscapefrom the head of the constellation
Scorpius.

About 600 light-years away, the nebulae are found
in the second version ofthe Sharpless Catalogas Sh2-1 (left, with reflection
nebulae VdB 99) and Sh2-7. At that distance, this field of view is about 40
light-yearsacross.